1. Field of the Invention
This invention relates to cleaning machines and, more particularly, to a water extraction cleaning machine having a mixing valve adapted to create cleaning solution mixtures of variable constituent ratios.
2. Description of the Related Art
Water extraction cleaning machines have long been used for removing dirt from surfaces such as carpeting, upholstery, drapes, and the like. The known water extraction cleaning machines can be in the form of a canister-type unit as seen in U.S. Pat. No. 5,237,720 to Blase et al. or an upright unit as seen in U.S. Pat. No. 5,500,977 to McAllise et al. and U.S. Pat. No. 4,559,665 to Fitzwater.
The current water extraction cleaners can be difficult to use and often have limited adaptability for a variety of cleaning conditions. For example, none of the known water extraction cleaners provide means for quickly and efficiently varying the mixture ratio of detergent and water. In addition, none of the known upright water extraction cleaners provide means for automatic adjustment of the height of the roller-type agitation brush in response to changes on the surface being cleaned. Another problem inherent with the known water extraction cleaners is ease of use in filling and emptying the clean water tank and recovery tank. Finally, none of the known prior art water extraction cleaners incorporate means for quickly and easily converting between on-the-floor cleaning and off-the-floor cleaning with an accessory hose and cleaning tool.